Randall RG100ES Reverb

[Wired-fr]

Hi folks,
sorry for my bad English, i'm French ,

We have à RG100ES for maintenance, amps have already had many repairs...
Reverb not working on this amp, only hisss and the sound becomes very treble when turn knob.
If i touch springs with my fingers, i can listen reverb, problem seems come to input tank
crushed signal.

Input's and output values on tank seems correct, ref tank is:
-> OC electronic Milton WIS 53563

But on schematic, is à type 4, but this amplifier, is a type 9 ( 3 springs), i think is bad tank setup inside,
We have contact Randall, but Randall's tech don't know reference exactly for this tank ... say only type 4 ...

Does someone have more informations or reference replacement for this tank ?

Thanks in advance

[Enzo]

Your English is a lot better than my French.

The number of springs is irrelevant. All that matters to the amp is the impedances.

Can you post or link a schematic?

If the two transducers in the reverb unit have resistances that seem OK, then likely the pan is not the problem, look to the drive circuit in the amp.

[Wired-fr]

Thanks for your reply

I told myself the same thing, but, have signal trace on my scop to output drice reverb,
have remplace IC, but always same problem ,

reverb values : input = 165R output 200R

Regards

https://el34world.com/charts/Schemat...dall_rg100.PNG

[Enzo]

Do you have any other amps there with reverb pans? Specifically 4EBxxxx, not 4ABxxxx. And if so could you substitute it into this amp for testing?

[Wired-fr]

I can look this tomorrow, not at workshop, have many amplifier with reverb, i look this and come back to you

thanks for your help En

[Wired-fr]

sorry impossible to edite my last post ...

I have found the problem, tech who repaired the amp was wrong,
it reversed the signal and the ground on the two faston terminals on output signal drive reverb ... it's been a long time that this is so. ( gound on pcb in not wiring, piste is cut for groud loop i think ... )

Reverb working now...

Thanks again for your help